Wherever you go just make sure you don’t get +4 on your band measurement- that will mean you’re in a too big band and a too small cup.
A lot of us pre op used to wear bands too big and a smaller cup and were fine with that as we had no boobs!
Now you e got them you need to support them.
I used to wear a 36A/34B but not really fill the B
Now I wear a 32E/F but in some bands that are very stretchy a 30FF
I’m a broad size 12 with a wide rib cage. My tight under measurement is 30.5 and my snug is 31.
Over bust standing is 37 inches
Over bust leaning is 38
Victoria secrets try and put me in a 34DD (I buy 32DDD)
M&S try and put me in a 36D (I wear 30F or FF in their bras)